Mandela, who was rushed to hospital in the early hours of Saturday (June 8) morning, is said to be in a "serious but stable" condition according to a government statement.

The hospital stay is his fourth since December, and there is a growing realisation among South Africa's 53 million people that they will one day have to say goodbye to the father of the "Rainbow Nation" that Mandela tried to forge from the ashes of apartheid.

Senior archivist at the centre Razia Saleh says all of Mandela's presidential gifts and other memorabilia are kept at the centre.

"This place here is where we keep all Madiba's art and gifts in awards collections, so it is very precious," she said.

"Over the years, Madiba, especially at the time of his birthday and during Christmas and throughout the years he received lots of gifts. So we have a process by which we gather them and add them to the permanent gift collection and this is where they are stored," she continued.

Before his release in 1990 Mandela spent nearly three decades in prison for conspiring to overthrow the apartheid government.

"I think we are very privileged and very lucky to be able to work with all this material on a daily basis. I think we feel very honoured that we are given an opportunity to do that," Saleh added.

Mandela stepped down as president in 1999 after one term in office and has been removed from politics for a decade. His last appearance in public was at the final of the soccer World Cup in Johannesburg in 2010.

International and local media have assembled in front of the Mediclinic Heart Hospital in the capital, Pretoria, where Mandela is staying and receiving visits from close family.